The kernel uses SPRG registers for various purposes, typically in
low level assembly code as scratch registers or to hold per-cpu
global infos such as the PACA or the current thread_info pointer.
We want to be able to easily shuffle the usage of those registers
as some implementations have specific constraints realted to some
of them, for example, some have userspace readable aliases, etc..
and the current choice isn't always the best.
This patch should not change any code generation, and replaces the
usage of SPRN_SPRGn everywhere in the kernel with a named replacement
and adds documentation next to the definition of the names as to
what those are used for on each processor family.
The only parts that still use the original numbers are bits of KVM
or suspend/resume code that just blindly needs to save/restore all
the SPRGs.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently the kernel expects the additional four IBAT and DBAT registers
to be available, but doesn't enable these registers on 745x CPUs, which
have them disabled after reset. Thus set the HIGH_BAT_EN bit in HID0
register, if the corresponding MMU feature is defined.
Signed-off-by: Gerhard Pircher <gerhard_pircher@gmx.net>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Complete workaround for DTLB errata in e300c2/c3/c4 processors.
Due to the bug, the hardware-implemented LRU algorythm always goes to way
1 of the TLB. This fix implements the proposed software workaround in
form of a LRW table for chosing the TLB-way.
Based on patch from David Jander <david@protonic.nl>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
603 CPUs have the same issue that some 750 CPUs have in that they can crash
in funny ways if a store from an FPU register instruction is executed on a
register that has never been initialized since power on. This patch fixes
it by making sure all FP registers have been properly initialized at kernel
boot.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Also renamed temp.c to tau_6xx.c (for thermal assist unit) and updated
the Kconfig option description and help text for CONFIG_TAU.
Signed-off-by: Paul Mackerras <paulus@samba.org>
